'So sue me' is the most aggressive and challenging such phrase. It's used as a response in situations where someone is criticized for some antisocial or illegal activity and wants to display their lack of concern. In effect, they are saying 'okay, I know it's wrong but you'll get no apology from me - if you want to take it further go to law'. Of course, the expectation is that the misdemeanour is too slight to bother with a formal legal process. Alternatively, the person being complained of may be aiming to demonstrate their wealth and power by portraying themselves as someone who is well able to defend themselves in court and, if necessary, pay damages. Either way, the message is clear - 'Say what you like; I don't care'.

The earliest reference I can find is from the song 'Sue Me, Sue Me', in the musical 'Guys and Dolls'. This was a Broadway show in 1950 and released as a film in 1955. This was composed by Frank Loesser and sung in the film version by Frank Sinatra (as Nathan Detroit) and Vivian Blaine (as Miss Adelaide):

Detroit: Serve a paper and sue me, sue me, what can you do me? I love you. Give a holler and hate me, hate me, go ahead, hate me. I love you.
Adelaide: When you wind up in jail, don't come to me to bail you out.
Detroit: Allright already, so call a policeman. Allright already, it's true, you knew, so sue me, sue me, what can you do me. I love you.

In the original stage version the line 'you knew' was given as 'so nu'. Nu is a Yiddish word meaning (depending on who you ask) something like 'what did you expect?'. This gives some weight to the suggestion that several American correspondents of mine have made - that the phrase is Yiddish and was in common use by Jewish men in New York prior to 1950. That would fit with the meaning of the line in the song. Loesser was Jewish, was born in and died in New York, and would certainly be familiar with 'so nu'. 'So nu, so sue' is Loesser's kind of rhyme and the jump to 'so sue me' being Yiddish isn't a large one.

It wasn't widely used until it was picked up again in 1990s America. There is a long running legal dispute between the Beatles' Apple Corps and Apple Computer regarding trademark rights (1978 - 2006 and counting). In 1991 Apple Computer introduced a system sound into the Macintosh System 7 operating system - called 'Sosumi'.

By 2002 we were seeing lines like this - in the 'Humor' column in the Maryland newspaper The Capital:

"Products today have too many features. I know I've said this before. So sue me."

As the phrase gained popularity it began to be used in social situations and more often with irony than with belligerence. By 2004, the term was in use throughout the English-speaking world and had gained enough currency for the New York Game Factory to market a board game called 'So $ue Me!' - 'An exciting new legal board game that turns litigation into a game of fun.'

For those who like a challenge there's also a hot chili sauce called 'So Sue Me'. This is from the same stable as 'Crazy Jerry's Brain Damage Hot Sauce', so - don't sue me - you have been warned.